This research proposes to analyze the nucleoprotein organization of mammalian chromatin. Our goals are, (1) to fractionate the DNA-binding high affinity nonhistone chromosomal proteins from Hela cells and to define those which may be involved in control of gene expression, (2) to examine the presence and role of the nonhistone proteins in the chromatin subunits, i.e., the nucleosomes, and (3) to establish methods for studying the DNA-binding sites for these proteins. We shall also examine how covalent modification, e.g. phosphorylation/dephosphorylation, of the high mobility group of the nonhistone chromosomal protein may alter the nuclease sensitivity, hence conformation, of chromatin.